1. Field of the Invention
The present invention relates to a joining sheet, an electronic component, and a producing method thereof, to be specific, to a joining sheet, a method for producing an electronic component using the joining sheet, and an electronic component obtained by the method.
2. Description of Related Art
Conventionally, it has been known that a solder paste which contains solder particles made of tin-bismuth based solder or the like and an active agent such as a carboxylic acid is used in the joining of terminals of two pieces of wired circuit boards. The tin-bismuth based solder particles are capable of being melted at low temperature. However, a solder joining portion which is formed by heating the tin-bismuth based solder particles to be melted has a low shock resistance and a low joining reliability. Therefore, in order to improve these properties, a solder paste which contains a thermosetting resin such as an epoxy resin in addition to the above-described solder paste has been proposed (ref: for example, Japanese Unexamined Patent Publication No. 2006-150413).
In Japanese Unexamined Patent Publication No. 2006-150413, the solder paste is applied to the surface of a terminal by a screen printing or the like and next, another terminal is brought into contact with the solder paste to be then heated. In this way, the solder particles are easily melted by the active agent, and the solder joining portion which is formed of the solder particles and a resin layer which is formed around the solder joining portion and reinforces the solder joining portion by allowing the thermosetting resin to cure are formed, so that the two terminals are solder joined.